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Stock-Based Compensation Expense - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 15, 2017
Mar. 31, 2017
Mar. 16, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period   4 years  
Number of common stock repurchased   4,975  
Purchase price of common stock by employees (as a percent)   85.00%  
Employee Stock Purchase Plan [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Employee withholding percentage   15.00%  
Restricted Stock And Restricted Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized compensation expense   $ 32,784,368  
Unrecognized compensation expense, recognition period   3 years 1 month 6 days  
Options to Purchase Common Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized compensation expense, recognition period   3 years 1 month 6 days  
Unrecognized compensation cost, stock options   $ 14,700,000  
Stock options vested, fair value   $ 1,000,000  
Stock options granted, weighted-average grant date fair value   $ 6.46  
Employee Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Common stock issued to employees (in shares) 138,085    
Aggregate proceeds from issuance of common stock to employees $ 1,500,000    
Share issued, price per share (in dollars per share) $ 12.79   $ 10.60
Closing price of shares issued (in dollars per share) $ 15.05   $ 12.47